This invention relates in general to vehicular brake systems, and in particular is concerned with a control valve mounted in a hydraulic control unit of an electronically controlled brake system.
Electronically-controlled brake systems for vehicles are well known. One type of electronically-controlled brake system includes a hydraulic control unit (HCU) connected in fluid communication between a master cylinder and a plurality of wheel brakes. The HCU includes a housing containing control valves and other components for selectively controlling hydraulic brake pressure at the wheel brakes.
Control valves for HCU's are commonly formed as electronically actuated solenoid valves. A typical solenoid valve includes a cylindrical armature slidably received in a flux tube or sleeve for movement relative to a valve body. A spring may be used to bias the armature in an open or closed position, thereby permitting or blocking fluid flow through the valve, respectively. A coil subassembly is provided about the flux tube. When the valve is energized, an electromagnetic flux generated by the coil subassembly slides the armature from the biased open or closed position to a closed or open position, respectively.
Control valves mounted in a HCU are actuated by an electronic control module to provide desired braking functions such as anti-lock braking, traction control, and vehicle stability control.
It is desirable that a control valve provides fluid control in a manner proportional to the amount of current applied to the coil subassembly. Such proportional control valves result in enhanced performance of an electronically controlled brake system.